Musical instrument



June 4, 1940.

L. HAMMOND MUSICAL INSTRUMENT 5 Sheets-Sheet 1 Filed March 8, 1940fm/erz for La ure/gfiammomi \8 1 flfiw W June 4, 1940. M D 2,203,569

MUSICAL INSTRUMENT Filed March 8, 1940 5 Sheets-Sheet 2 v l 44 n 5% 42 JL [III/JIM r III a EMT TIIIH 1 II II r;

[/2 were for Laure/2s Hammond June 4, 1940. L, M D 2,203,569

MUSICAL INSTRUMENT Filed March 8, 1940 5 Sheets-Sheet 3 f 1 W! n arm]21% :m m

. [/2 1/ e)? for I %la ureresfiammond 5 Sheets-Sheet 4 r22 1.. HAMMOND am M f. 3 3 e mW MW 4 "mm a 2 wk 5 H m." fi [NO/W n m M w E w UH f "a n ag M z w MUSICAL INSTRUMENT Filed March 8, 1940 Patented June 4, 19402,203,569

UNITED STATES PATENT OFFICE MUSICAL INSTRUMENT Laurens Hammond, Chicago,Ill.

Application March 8, 1940, Serial No. 322,903

12 Claims. (Cl. 84-425) My invention relates generally to musicalinshowing an adjustable mounting for the keystruments, and moreparticularly to improved board of the electrical portion of theinstrument;

keyboards and controls for combination musical Figure 13 is a sideelevational view of the keyinstruments, such as combination piano andelecboard for the electrical portion of the instrutrical musicalinstruments. ment attached to the piano portion thereof, the 5 It is anobject of my invention to provide an latter being shown in fragmentarysection; improved keyboard for an electrical musical in- Figure 14 is afragmentary sectional view taken strument which may beattached to andform a on the line l4--I4 of Fig. 12; and, part of a piano, so as to beoperated therewith as Figures 15, 16, 17 and 18 show the positions of anintegral part thereof. the player's hands on the keyboards of the com-10 A further object is to provide an improved keybination instrument.board for a combination piano and electrical mu- Music which may beprovided by a piano has sical instrument upon which the performer maysubstantially universal appeal, and the piano is easily play bothportions of the instrument sitherefore recognized as one of the mostdesirable multaneously, and render selections incapable of and popularof musical instruments. There are, rendition separately on eitherportion of the inhowever, a number of limitations inherent in strument.music produced by pianos. The fact that piano A further object is toprovide an improved tones cannot be sustained indefinitely, that theykeyboard for electrical musical instruments always have a percussiveattack, that they do; 20 which may be easily attached to and combinednot provide a clearly perceptible vibrato, and that 20 with a standardpiano without defacing the latit is diflicult to execute passagesproperly when ter. played pianissimo makes it desirable that piano Afurther object is to provide an improved keytones be supplemented andreinforced by tones board for electrical musical instruments whichhaving these characteristics which are lacking 52.: includes variouscontrols, which is very comfrom piano music. These lattercharacteristics pact, and which, when attached to a piano, does mayreadily be obtained by a variety of electrical not interfere in any waywith the normal use systems for tone generation and control, and it ofthe piano, but is capable of simultaneous use is therefore one of thebroader objects of my intherewith. vention to provide a piano with anadditional Other objects will appear from the following keyboardcontrolling the operation of an electri- 30 description, reference beinghad to the accomcal musical instrument in which the keyboard panyingdrawings in which: and controls for the electrical part of the in-Figure 1 is a side elevation of the combined strument are so located andpositioned that the electrical musical instrument and grand typepiperformer may easily play upon both keyboards anoportions of thelatter being broken away simultaneously. The keyboard of the' electrical35 more clearly to show the keyboard for the elecpart of the instrumentdoes not in any way intrical portion of the instrument; terfere with theplayers normal piano tech- Figure 2 is a perspective view of theelectrical nique. portion of the musical instrument combined with Whilethe instrument may be made initially 40 an upright type piano; with bothkeyboards, I prefer to make the key- 40 Figure 3 is a vertical sectionalview of the keyboard for the electrical portion of the instrument boardsof the instrument; as a unit which may be attached to any stand- Figure4 is a fragmentary horizontal sectional ard piano and detached therefromwithout marview taken on the line 4-4 of Figure 3; ring the normallyvisible portions of the piano Figure 5 is a fragmentary verticalsectional case. 45 view taken on the line 5,-5 of Figure 3; The designof the cases of pianos of various Figure 6 is a fragmentary plan view ofthe manufacture differ considerably. Not only the keyboards of theinstrument; contour of the front surface oeneath the key- Figure 7 is afragmentary front elevational board, but also the distances from thetops of view of the keyboards of the instrument; the keys to the bottomsurface of the bed plank, 50

Figures 8, 9, 10 and 11 are fragmentary secvary over a considerablerange. To be fully use-- tional views showing the keyboard for theelecful for cooperation with the keys of the piano, trical portion ofthe instrument attached to pithe keys of the electrical instrumentkeyboard anos having various front contours; should be located closelyadjacent and prefer-' Bl Figure 12 is a fragmentary bottom planview ablyslightly below the piano keys. By the keyboard construction disclosedherein, this space relationship of the two keyboards may be readilyobtained. Due to the size, shape and arrangement of the keyboard of theelectrical portion of the instrument, it may be readily attached topractically any piano commercially produced.

With the keyboard of the electrical portion of the instrument attachedto the piano in the manner herein disclosed, this keyboard does notappreciably reduce the leg room available, nor do the keys in any wayinterfere with the normal use of the piano keyboard.

Referring to Figures 1 and 2, the instrument comprises generally a pianocase ill, which may be of the upright type shown in Fig. 2, or of thegrand type shown in Fig. 1, in each case having the usual keyboard 62and pedals M. The piano may be of any desired or conventionalconstruction, and generally will include the usual name board [5, frontrail Iii, and music rack 20.

The keyboard for the electrical portion of the instrument, designatedgenerally by the reference character 2!, may be immovablysecured to thepiano portion of the instrument, as shown in Fig. 3, or may beadjustably secured thereto as shown in Figs. 12, 13 and 14. The keyboardis supported by a pair of channel-shaped brackets 22 which form conduitsfor wires 23 connecting the keyboard with the other parts of theelectricalportion of the instrument.

In Fig. 3, the flange of the supporting bracket 22 is shown as beingsecured to the keyboard bed plank 26 by screws 25.

In the modified form of the invention shown in Figs. 12, 13 and 14, thechannel-shaped brackets 22 are connected together by a channel .26 whichis riveted to the brackets 22, the channel 26 having a pair of elongatedslots 27. A bar 28 is secured to the keyboard bed plank with screws 29,the bar 28 being tapped to receive a pair of clamping thumb screws 30which project through the slots 27, and are adapted to clamp the channel26 in the position in which the latter is shown in full lines in Fig.12, in the position in which the parts are shown in the dotted lines insaid figure, or in any intermediate position. The slots are preferablysufficiently long that the keyboard may be moved a distancecorresponding to one octave of keys on the piano, for reasons which willappear hereinafter.

A box 32 which may form an enclosure for certain of the parts of theelectrical portion of the instrument, is rigidly secured to the brackets22 and thus moves with the latter as the keyboard is shifted. The box 32and its contents may counterbalance the keyboard 2|, thus making thekeyboard more easily shiftable upon its adjustable support. A lever 34is preferably mounted upon the box 32, being adapted to control theoverall volume of the electrical portion of the in strument. It ispivotally mounted so that it may be engaged by the knee of the musician,and readily swung back and forth to control the expression. For thispurpose, the lever .is preferably spring-biased to assume the positionin which it is shown in Figs. 12 and 13.

The electrical portion of the instrument is contained mainly in arelatively flat cabinet 36, which is connected to the box 32 by cables3?, as shown in Fig. 1. The cabinet 36 may be suitably secured beneaththe case of a grand type of piano in the manner indicated in Fig. 1, ormay be suitably positioned adjacent the piano, especially when combinedwith an upright piano as shown in Fig. 2. The cabinet 36 preferably hasgrill openings 38 formed therein for the loud speaker located within thecabinet 36.

As shown in Fig. 3, the piano keyboard comprises the usual black sharpand fiat keys 40, and the usual white keys 4!. These keys are mounted inthe usual manner upon the keyboard bed frame 42, which is supported bythe bed plank 24.

The keyboard 2| comprises black keys 43 and white keys M. These keys arevery much shorter than the corresponding keys 40, H, but are of the samewidth and spacing as the latter. The keyboard 2| is assembled upon andpartially enclosed by a casing plate having a horizontal portion 46, alower rear wall portion 4? and an upper rear wall portion 48, theportion 48 being offset rearwardly with respect to the wall portion M.The casing plate 46, 41, 48 may extend the full length of the keyboard2|.

The keys 43, 44 are preferably molded of a suitable plastic composition,and have switch actuators 50 suitably secured thereto by screws 52threaded in bosses 54 formed on the keys. The screw 52 passes throughone end of a leaf spring 56, the other end of which is suitably securedto a rigid frame plate 53. Another leaf spring 60 is clamped to a rigidframe plate 62 at one end, and has an aperture to receive a tip 64projecting from an insulating member 66, which is riveted to theactuator 50. The springs 56 and 60 form the sole means for supportingand guiding the key, and resiliently returning it to normal position.

The keys 43, 44 have comparatively short strokes, downward movementthereof being limited by their engagement with a felt stop 68. Thereturn strokes of the keys are limited by the engagement of theiractuators 50 with a felt strip 10. The actuator 50 is provided for theoperation of switches i2, M or any other additional switches which maybe required for the operation of the electrical portion of theinstrument.

Pivoted stop tablets 16 are provided for the actuation of switches I8and 80. These tablets form the actuating means for various controls ofthe electrical portion of the instrument. The tablets 16 are relativelywide and spaced closely adjacent each other so that they in effect formthe front wall of the keyboard 2|. A strip 82 bearing suitableidentifying legends for the tablets 16 is located above the tablets 16.Some of these tablets are employed to shift the register of thekeyboard, and as, for example, the tablets marked Bass, Tenor, Contraltoand Soprano. three octaves of keys of the keyboard 21 will control notesin the bass register, e. g., notes 01 to B3 (using a common system ofnote designation,

as shown in applicant's prior Patent No. 1,956.-

350); when the tenor tablet is operated keys will control notes C2 toB4; operation of the contralto tablet will cause the registerv of thekeyboard to shift to the notes C3 to while operation of the sopranotablet will shift the keyboard register to the notes C4 to B6. Thus,although the keyboard 2| includes but three octaves of keys, it may beused to play any note within a seven octave range by selective operationof the tablets 16.

Other tablets may be utilized to control such other effects as thevibrato, the rate of-attack, and the over-all timbre variation by anumber of resonant output circuits.

The front rails and adjacent portions of the keyboard bed planks ofpianos now in use, vary When the Bass tablet is operated, the

considerably in contour. The keyboard 2| is of course intended to beattached to any piano, and such attachment to pianos of difi'erent kindsis facilitated because of the shape of the casing plate 46, 41, 48.

It will be understood that it is desirable that the keys 43, 44 belocated sufficiently close to the keys 40, 4| that they may readily beplayed with the thumb, while the remaining fingers are resting upon thekeys 40, 4|. The facility with which this relationship between the twokeyboards is obtained, in attaching the keyboard 2| to various makes ofpianos, is shown by the diagrammatic illustrations in Figs. 3 and 8 to11 inclusive.

In Figure 8, the keyboard 2| is illustrated as being attached to a pianoin whichthe distance from the keys to the bottom surface of the keyboardbed plank is unusually great. In attaching the keyboard 2| to a piano ofthis type, a spacer 84 is inserted between the brackets 22 and thekeyboard 2|, so as to raise the keys 43 44 of the latter to a suitableplaying position.

In Fig. 9, a piano having a front rail of stepped contour is shown, thisfigure illustrating how the keys 43, 44 are nevertheless positionedclose to the piano keys, principally by virtue of the fact that theoffset portion 48 of the casing for the keyboard 2| over-hangs a portionof the front rail, and because the keys 43. 44 extend rearwardly of thecasing wall 41, and thus also overlie a portion of the front rail.

Fig. 10 illustrates how the keyboard is readily supported by thebrackets 22 even though the front rail of the piano has a recedingcontour.

Fig. 11 shows a keyboard 2| attached to a piano in which the distancebetween the keys and the lower surface of the keyboard bed plank isunusually short. to this type of piano, the brackets 22 may be spacedfrom the lower surface of the keyboard bed plank by spacers 86, so thatthe keys 43, 44 lie at the proper lever with respect to the piano keys4|.

From a consideration of Figs. 3 and 8 to 11 inclusive, it will beapparent that the keyboard 2| may be attached to practically any pianocommercially made, with the keys 43, 44 in suitable playing positionwith respect to the keys 4 I, since said figures show extreme variationsin front rail construction rather than the normal variations found in alarge majority of pianos now in use or on the market.

The electrical portion of the instrument, as distinguished from theparts which are manually operated to control the sound output of theinstrument, does not form a part of the invention claimed herein, and istherefore not illustrated or described in detail. It will be understoodthat the keyboard 2| may be used to control the operation of any musicalinstrument operable by remote control, and which will produce musicwhich will be harmonize with that produced by the piano. Suchinstruments may take any one of innumerable forms, such as disclosed,for example, in the co-pending application of John M. Hanert, Serial No.274,325, filed May 18, 1939, or in the co-pending application of LaurensHammond and John M. Hanert, Serial No. 293,444, filed September 5,'1939. The electrical portion of the instrument is preferably of themelody type in which but a single note (with or without coupled octavenotes) may be sounded at one time, and is preferably so arranged thatwhen two or more keys are simultaneously In securing the keyboard 2|.

depressed, the note corresponding'to the lowermost of the depressed keyswill be sounded, while any other higher keys which may be depressed atthe same time will have no eifect upon the tone produced.

The generators of the electrical impulses, the power supply system, theamplifier, the loud speaker, the quality changing means, and all otherparts of the electrical portion of the instrument, with the exception ofthe main switch, the key and tablet operated switches, and theexpression or volume controlling means, are preferably mounted in thecabinet 36.

Other circuits for instruments of this general type are disclosed in thepatents to Smiley Re. 20,831, to De Forest No. 1,543,990, and toYungblut No. 2,045,172.

The constructional features of the key action and key switches are notfully disclosed herein,

' but are fully disclosed and claimed in the copending application ofLaurens Hammond and George H. Stephens, Serial No. 333,824 filed May 7,1940.

In playing the instrument described above, the electrical portion of theinstrument may be used to play the melody portion of the score in oneregister, while the standard piano portion of the instrument is utilizedto play the accompaniment. In the preferred form of the electricalportion of the instrument, the tablets 16 may be utilized to change theregister of the tones produced upon depression of the keys 43 and 44, asset forth above, and to change the quality or other characteristics ofthe tone, so that the melody portion of the score may be rendered easilyirrespective of the register in which it appears.

Upon other occasions, the keys 43, 44 may be struck simultaneously withthe depression of corresponding keys 40, 4| of the piano keyboardiinwhich case the tones produced by the electrical portion of theinstrument will combine with the tones produced by the piano strings tosupplement and enrich the latter, causing new composite tones. When, asabove described, the electrical portion of the instrument has tabletcontrols whereby the tone quality of the instrument may be readilychanged, a large variety of different composite tones may beproduced'when the keys of the piano are depressed simultaneously withthe depression of keys 43, 44.

When the speaker is located as shown in Fig. 1, the tones producedthereby will cause some vibration of the sounding board of the piano,and when the sustaining pedal of the piano is in a depressed position,will cause sympathetic vibration of the piano strings.- Due to thisinteraction of the sound producing elements of the two portions of theinstrument, the composite tones produced may be of a decidedly differentcharacter than could be obtained by either portion of the instrument ifdissociated from the other. Thus, to a limited extent, the sustainingpedal of the piano may be used to control the envelope of the toneproduced by the electrical portion of the instrument.

Due to the location of the expression or volume control lever 34, it maybe operated by the knee of the musician without in any wev interferingwith his operation of the sustaining pedal of the piano portion of theinstrument. In a preferred form of the invention the lever 34 is used tooperate the main switch by which the electrical portion of theinstrument is connected to the source of electrical energy.

The keys 43, 44 may be depressed by pressure exerted on the rearward aswell as upon the forward ends thereof, and the simultaneous depressionof these keys with the depression of the piano keys 40, 4| is thusfacilitated. Such operation of the instrument is also made easierbecause of the fact that the rearward portions of the keys 43, 44over-hang a portion of the piano, or in other words, project rearwardlybeyond the main portion of the rear wall 4'! of the keyboard casing.

The arrangement of the tablets 16 also facilitates the operation of theelectrical portion of the instrument, since in most instances thesetablets may be operated by the thumb of the player without moving hishand far from its normal playing position. The tablets also form theexternal front wall of the keyboard, improving the appearance thereofand making itunnecessary to provide a relatively costly finished frontsurface. Due to the compact arrangement of the keys 43, 44 and tabletsit with respect to the piano keys 40, 4|, the instrument may be playedwith a minimum of effort and without requiring the mastery of a playingtechnique dilfering greatly from that of the pianist.

When the same note is simultaneously played upon the piano keyboard andthe keyboard of the electrical portion of the instrument, the compositetone will have a quality differing from the piano tone as well as fromthe tone of the electrical portion of the instrument. The composite tonewill likewise have an intensity envelope which may be made to differmaterially from that obtainableby producing the tone on either portionof the instrument separately. The piano tone is primarily percussive incharacter, and when such percussive tone is combined with a sustainedtone, such as may readily be produced by the electrical portion of theinstrument, the composite tone will produce an effect of a percussivetone merging into a sustained tone, which is very useful in therendition of many types of music.

To facilitate thumbing, that is, depressing the keys 43, 44 by means ofthe thumb while playing the piano keys with the remaining fingers of thehand, the black keys 43 may be made narrower than the black keys 4|] ofthe piano, so that a white key 44 located between two adjacent blackkeys 42 may be depressed easily by the thumb without depressing eitherof the adjacent black keys. This is not, however, essential, because theelectrical portion of the instrument may be arranged so that only thelowermost of two simultaneously depressed keys will be effective tocause sounding of a note. Ordinarily, the spacing between adjacent blackkeys of a piano keyboard is insufficient to permit depression of theintervening portion of the white key by a thumb of average size.

The operation of the instrument and the range of different resultsobtainable by its use may be more clearly described by reference tospecific examples of music which may be rendered upon the instrument.For example the left hand may be utilized to play the chord C1-C2, whilethe fingers of the right hand play the chord A3t-D4t-G4 and the thumb ofthe right hand plays the note D5t on the keyboard of the electricalportion of the instrument, namely the appropriate one of the keys 43.

As a second example the left hand may be used to play the chordD2-G2-B2-D3, the fingers of the right hand playing the chord G3-B3-D3while the right thumb plays the note D1 on the appropriate key 44.

From these two examples, it will be apparent that the thumb of the right'hand may be used to control the sounding of notes which could notpossiblybe played on the keyboard of a standard piano while holding theparticular chords designated.

In Fig. 15 the position of the players hands are shown in executing therendition of the chord Dlii-DZt with the left hand,the chordA3t-D4'ii-G4 with the fingers of the right hand and the note D5t withthe thumb of the right hand-a series of notes which could not besimultaneously played on a standard piano keyboard by a solo player.

In Fig. 16, in addition to the chords D2-G2- B2-D3 and B3-D4-G4 playedby the left hand and fingers of the right hand respectively, the thumbof the right hand is shown as depressing one of the keys 44 to cause thesounding of the note D1, assuming that the bass tablet 16 has beenoperated. If the tenor tablet had been operated the note D2 would besounded by the electrical portion of the instrument, while if thecontralto tablet had been operated the note D3 would be heard. Similarlyif the soprano tablet alone had been operated the note D4 would besounded. If all or several of the register controlling tablets labeledbass, tenor, contralto, and soprano are operated at one time the notesindicated above (namely D1, D2, D3 and D4) or various combinations ofthese notes, depending on the combination of tablets which are operated,will be sounded simultaneously.

In Fig. 17 the chord D2-G2-B2-D3 is being played by the left hand whilethe chord B3-D4-G4 is played with the fingers of the right hand. Thethumb of the right hand depresses a G key 44 which may result insounding the note G1, G2, G3 or G4, or any combination of these notes,depending upon whichof the register selecting tablets I6 has or havebeen operated.

In Fig. 18, the keyboard 2| is shown as shifted to the right thedistance of one octave of keys from its normal position. In this figurethe left hand is utilized to play the chord B2-D3-G3-B3 and the fingersof the right hand are shown as depressing the piano keys to play thechord G4B4-D5, while the thumb of the right hand plays the'note D2, orD1, D3, or D4, or any combination of these four notes, depending uponthe setting of the register controlling tablets '16, again illustrating,in different manner, how the keyboard 2|, due to its close proximity tothe piano keyboard, and due to the fact that its mounting is such thatit may be shifted longitudinally of the piano keyboard, makes itpossible to play simultaneously a series of notes spread over such awide range that they could not possibly be played by a solo player on apiano.

From a consideration of these examples of musical scores which may besatisfactorily rendered on the improved instrument, it will be apparentthat very many novel and interesting musical effects may be obtained bya single player, due particularly to the unique relationship between thekeyboard 2| and the piano keyboard. While the keyboard 2| does not inany way interfere with the use of the piano keyboard in a normal manner,it is so positioned that it may be conjointly used with the pianokeyboard to produce these novel and interesting musical effects.

Since the electrical portion of the instrument is so arranged that onlythe lowermost of two or more simultaneously depressed keys of thekeyboard 2! will be effective in causing sounding of a note, themusician need not exercise any particular care in the depression of keysof the keyboard 2| by his thumb, it being necessary only that he doesnot depress any keys lower than the one which he intends to have controlthe production of the tone. By virtue of this fact, a chromatic scalearpeggio may be rendered with great facility because, to produce thisresult, the musician need merely slide his thumb rapidly along thekeyboard.

The fact that the keyboard 2| has an off-set rear wall and that the keys43, 44 thus over-lie a portion of the front rail or other forwardlyprojecting part of the piano case, is an important factor in making itpossible to have the keys 43,44 so close to the piano keys that themusician can depress the keys of the piano keyboard, whilesimultaneously depressing a key of the keyboard 2| with his thumb.

Because the keys 43, 44 are mounted for substantially translatorymovement, the player can depress these keys by pressing downwardly uponthe rear ends thereof. The mounting of the keys 43, 44 in a manner suchthat they have substantially translatory vertical motion, and that theirstrokes are relatively short, are fac tors which contribute materiallyto the attainment of the primary objective of the invention, namely,making it possible easily to depress these keys with the thumb, whilethe remaining fingers of the hand may be used-to depress keys of thepiano keyboard. The two keyboards are so closely positioned that theyare within the span of a single hand, not only to the extent that bothkeyboards may be reached simultaneously by a single hand, but that bothkeyboards may be played upon simultaneously with such convenience asgreatly to facilitate such playing.

By defining the keys 43, 44 as having substantially translatory motion,I wish to distinguish from the usual pivoted keys in which the motion isrotatory. The key may be said to be capable of substantially translatorymotion when the pressure of the finger applied to at least one part ofits finger engaging surface will cause the key to move, in a manner suchthat at a given in-' stant, all points of the key will be moving insubstantially the same direction at substantially the same velocity,whether or not the key is so mounted as to be capable of otheradditional forms of movement.

While I have shown and described a particular embodiment of myinvention, it will be understood that the invention as illustrated anddescribed is merely exemplary, and that I desire to include within thescope of my invention, all such similar and modified forms of theinvention by which substantially the results of my invention may beobtained through the use of substantially the same or equivalent means.

I claim:

1. The combination of an electrical musical instrument with a pianohaving a keyboard, a keyboard case attached to said piano in closeproximity to and in front or the keyboard thereof, a plurality of keysof substantially the same width and spacing as the piano keys butappreciably shorter than the latter mounted on said case, said shortkeys having playing surfaces extending rearwardly to substantially therear edge of said case, and means attaching said case to said piano, theplaying surfaces of the two keyboards being within the convenientplaying span of a single hand.

2. In an electrical musical instrument, a keyboard case for attachmentto a standard piano in close proximity to and in front of the keyboardthereof, a plurality of keysof standard piano width and spacing butappreciably shorter than standard keys, said keys occupying the top ofsaid case and having playing surfaces extending rearwardly tosubstantially the rear edge of said case, and means on the case forattaching the same to said piano, whereby the two keyboards will liewithin the convenient playing span of a single hand.

3. In an electrical musical instrument, a keyboard frame for attachmentto a standard piano in close proximity to and in front of the keyboardthereof, a plurality of keys of substantially standard piano width andspacing but appreciably shorter than standard piano keys, means in saidframe supporting said keys for individual vertical substantiallytranslatory motion, said keys having playing surfaces extendingrearwardly to substantially the rear edge of said frame, and means forattaching said frame to said piano, whereby the two keyboards will liewithin the convenient playing span of a single hand. I

4. In an electrical musical instrument, a keyboard supporting frame forattachment to a standard piano, a plurality of keys carried by saidframe and of substantially standard piano width and spacing butappreciably shorter than standard keys, said keys having playingsurfaces extending rearwardly to a straight line, and means forattaching said supporting frame to said piano whereby said line falls infront of and close to the front ends of the'keys of the piano keyboard,and so that the two keyboards will lie within the convenient playingspan of a single hand.

5. The combination of an electrical musical instrument with a pianohaving a keyboard, a keyboard case attached to said piano in closeproximity to and in front of the keyboard thereof, a plurality of keysof substantially the same width and spacing as the piano keys butappreciably shorter than the latter, said short keys having playingsurfaces extending rearwardly to substantially the rear edge of saidcase, means attaching saidcase to said piano, with the two keyboardswithin the convenient playing span of a single hand, said meansincluding a bracket having its forward end attached to said case andextending rearwardly beneath and attached to the keyboard bed plank ofthe piano.

6. In an electrical musical instrument, a keyboard case for attachmentto a standard piano in close proximity to and in front of the keyboardthereof, said case having a rear wall, a plurality of keys of standardpiano width and spacing but appreciably shorter than the standard keys,said keys having playing surfaces extending rearwardly beyond a portionof the rear wall of said case, and means for attaching said case to thepiano, whereby the keyboard will be held in such position with respectto the piano keyboard that both keyboards will lie within the convenientplaying span of a single hand.

7. In an electrical musical instrument, a keyboard case for attachmentto a standard piano in close proximity to and in front of the keyboardthereof, a plurality of keys of substantially standard piano width andspacing but appreciably shorter than the latter, said keys havingplaying surfaces extending rearwardly to substantially the rear edge ofsaid case, means for attaching said case to a standard piano, wherebythe two keyboards will lie within the convenient playing span of asingle hand, and a plurality of register controlling tablets mounted onsaid case, whereby the range of notes playable on one of said keyboardssimultaneously with the playing of a given note on the other of saidkeyboards by the one hand is greatly extended.

8. In an electrical musical instrument, a keyboard frame for attachmentto a standard piano in close proximity to and in front of the keyboardthereof, a plurality of keys of substantially standard piano width andspacing but appreciably shorter than the latter and mounted on saidframe for vertical substantially translatory motion, said keys havingplaying surfaces extending rearwardly to substantially the rear edge ofsaid frame, means for attaching said frame to said piano, whereby it ispositioned so that the two keyboards lie within the convenient playingspan of a single hand, and a plurality of tablets pivoted on the frontof said case, said tablets being located closely adjacent each other soas to form substantially the whole of the front wall of said case;

9. In an electrical musical instrument, a keyboard frame for attachmentto a standard piano in close proximity to and in front of the keyboardthereof, said frame'having a rear wall with a rearwardly offsetupperportion, a plurality of keys of substantially standard piano widthand spacing but appreciably shorter than standard keys, said keys havingplaying surfaces extending rearwardly beyond the main portion of saidrear wall of said frame, and means for attaching said frame to saidpiano, whereby the two keyboards are positioned to lie within theconvenient playing span of a single hand.

10. In an electrical musical instrument,.a keyboard case for attachmentto a standard piano in close proximity to and in front of the keyboard.thereof, a plurality of keys of standard piano width and spacing butappreciably shorter than standard keys, said keys occupying the top ofsaid case and having playing surfaces extending rearwardly tosubstantially the rear edge of said case, means on the case forattaching the same to said piano, whereby the two keyboards will liewithin the convenient playing span of a single hand, and a plurality ofcontrol tablets forming the front wall of said case. I

11. In an electrical musical instrument, a keyboard case for attachmentto a standard piano in close proximity to and in front of the keyboardthereof, a plurality of keys of substantially standard piano spacing butappreciably shorter than standard keys, said keys occupying the top ofsaid case and having playing surfaces extending rearwardly tosubstantially the rear edge of said case, arid means on the case forattaching the same to the piano, whereby the two keyboards are held inclose proximity and within the convenient playing span of a single hand.

12. In an electrical musical instrument, a keyboard case for attachmentto a standard piano in close proximity to and in front of the keyboardthereof, a plurality of keys of substantially standard piano spacing butappreciably shorter than standard keys, said keys occupying the top ofsaid case and having playing surfaces extending rearwardly tosubstantially the rear edge of said case, and adjustable means forattaching said keyboard to the piano, said means including a slidingconnection between a part thereof

